1. Field of the Invention
The present invention relates to a method of producing a fluorescent screen of a cathode-ray tube (CRT) and, more particularly, to a method of forming carbon stripes or fluorescent layers on an inner surface of a CRT panel in a monochromatic or color television receiver.
2. Description of the Prior Art
It is generally customary that a fluorescent screen of a CRT panel in a color television receiver or the like is produced in the following procedure.
First the inner surface of the panel is coated with carbon and then is dried. The carbon film thus dried is exposed and developed in a manner to form carbon stripes having a predetermined width and a predetermined pitch.
Subsequently the entire inner surface of the panel is coated uniformly with a fluorescer over the carbon stripes and then is dried.
Thereafter an aperture grill with fine vertical striped slits is attached to the inner surface of the panel, which is exposed to a fluorescent light source and then is developed to produce a fluorescent screen of a first color.
Similarly to the above, second-color and third-color fluorescers are sequentially applied, dried, exposed and developed to produce a fluorescent screen of three primary colors (R, G, B).
In such carbon stripes, the line width is strictly regulated in view of contrast and so forth. Normally, panels with carbon stripes are periodically extracted by measurer on a random sampling basis, and the line widths of the carbon stripes are visually inspected by means of a microscope. The result of such measurement is fed back to an exposure table where the carbon film dried on the inner surface of the panel is exposed to a light source, so that the line width of each carbon stripe is regulated under control while changing the exposure in accordance with the measured value.
However, due to the operation of measuring the line widths of the carbon stripes by means of a microscope, it is unavoidable that some level differences are caused among individual measurers to consequently bring about variations in the line widths of the carbon stripes. Furthermore, measurements need to be performed in several portions of the panel for detecting whether the line widths are uniform or not over the entire panel, and the time required for such measurements comes to be extremely long because of the visual inspection, so that the working efficiency is rendered low. In addition, a complete result is not achievable in such periodic measurements since it is impossible to follow up any line width variations that occur during the interval of the visual inspections.